What kind of cable is this? (Please help)

That is a serial mouse cable. You may be able to find an adapter to go from that to a USB A socket.

An adapter is available however [IMO] it would be much better to just purchase modern hardware. Here is a link to a female serial to usb connector;
http://www.newegg.com/Product/Produ...rial_female_to_usb-_-9SIA25V23A7757-_-Product
Remember you still have to have drivers for this device to work. You cannot just plug it in and expect it to work; most likely NOT going to happen. Any old device like this is probably not going to have drivers available for a modern operating system ie win10, win8, etc. Before purchasing the above part, go to the support site of whatever hardware you are attempting to connect and see if there are drivers available.

Alright thank you, would this plug in easily on an older desktop?

Actually, that's a PC gameport connector. Used for Joysticks and gamepads, ports were often found on soundcards where they doubled up as MIDI ports. There were some USB adapters but I think that, even with these, support was dropped in Vista and later.